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Aug. 25, 2011 -- Half of U.S. adults will be obese by 2030 if current trends continue, a new report shows.

About one in three adults in the U.S. are obese today. That figure will rise to half of American adults by 2030 if little is done to address the obesity epidemic, Columbia University researcher Claire Wang, PhD, said today at a news briefing in London.

"Our projections find that rising obesity is going to result in increases in many of these chronic diseases which are disabling and expensive to treat," Wang said. "We have to act fast."

The briefing highlighted a special obesity edition of the The Lancet, published online today.

Impact of Increase in Obesity

Wang says expenditures to treat obesity-related diseases will cost the U.S. health care system up to an extra $66 billion each year by 2030, if the projections become reality.

Wang and colleagues from Columbia University and England's University of Oxford constructed a mathematical model to project obesity rates in the U.S. and U.K. over the next two decades.

If, as they predict, 164 million Americans are obese by 2030, Wang says the health care burden will include:

An additional 8 million cases diabetes

6.8 million additional cases of heart disease and stroke

Over 0.5 million cases of cancer

Stopping the Trend

Those predictions don't have to come true. Even very modest weight reductions at the population level could have a dramatic -- and positive -- effect, Wang says.

For instance, the researchers calculate that just a 1% reduction in body mass index (BMI) at the population level would prevent as many as 2.4 million cases of diabetes and 1.7 million cases of heart disease and stroke.

Another report, from experts at the Harvard School of Public Health, shows that even though obesity has been rising globally for decades, efforts to address the problem have been lacking.

Researcher Steven L. Gortmaker, PhD, says a coordinated effort that includes the private sector is needed, but national governments must lead the effort, just as they have with tobacco control.

Cigarette taxes led to dramatic declines in smoking. Gortmaker and colleagues contend that taxing unhealthy foods -- especially sugar-sweetened beverages -- could have a big impact.

In an interview with WebMD, Gortmaker conceded that most Americans might not favor such a tax.

"No single government has really taken the lead on this issue and certainly in the United States an excise tax on sugar-sweetened beverages might not be particularly popular," he says "But it could have a big impact on obesity rates and on the overall health of the population."